The line chart requires an array of labels for each of the data points. This is shown on the X axis.
The data for line charts is broken up into an array of datasets. Each dataset has a colour for the fill, a colour for the line and colours for the points and strokes of the points. These colours are strings just like CSS. You can use RGBA, RGB, HEX or HSL notation.
The label key on each dataset is optional, and can be used when generating a scale for the chart.
### Chart options
These are the customisation options specific to Line charts. These options are merged with the [global chart configuration options](#getting-started-global-chart-configuration), and form the options of the chart.
// Function - if specified this is passed the tick value, index, and the array of all tick values. Returns a string that is used as the label for that value
For example, we could have a line chart display without an x axis by doing the following. The config merge is smart enough to handle arrays so that you do not need to specify all axis settings to change one thing.
// This will create a chart with all of the default options, merged from the global config,
// and the Line chart defaults, but this particular instance will have `bezierCurve` set to false.
```
We can also change these defaults values for each Line type that is created, this object is available at `Chart.defaults.Line`.
### Prototype methods
#### .getPointsAtEvent( event )
Calling `getPointsAtEvent(event)` on your Chart instance passing an argument of an event, or jQuery event, will return the point elements that are at that the same position of that event.
```javascript
canvas.onclick = function(evt){
var activePoints = myLineChart.getPointsAtEvent(evt);
// => activePoints is an array of points on the canvas that are at the same position as the click event.
};
```
This functionality may be useful for implementing DOM based tooltips, or triggering custom behaviour in your application.
#### .update( )
Calling `update()` on your Chart instance will re-render the chart with any updated values, allowing you to edit the value of multiple existing points, then render those in one animated render loop.
```javascript
myLineChart.datasets[0].points[2].value = 50;
// Would update the first dataset's value of 'March' to be 50
myLineChart.update();
// Calling update now animates the position of March from 90 to 50.
```
#### .addData( valuesArray, label )
Calling `addData(valuesArray, label)` on your Chart instance passing an array of values for each dataset, along with a label for those points.
```javascript
// The values array passed into addData should be one for each dataset in the chart
myLineChart.addData([40, 60], "August");
// This new data will now animate at the end of the chart.
```
#### .removeData( )
Calling `removeData()` on your Chart instance will remove the first value for all datasets on the chart.
```javascript
myLineChart.removeData();
// The chart will remove the first point and animate other points into place
